Selenomethionine chiral speciation in yeast and parenteral solutions by chiral phase capillary gas chromatography-ICP-MS

Abstract

Chiral resolution and speciation of DL-selenomethionine enantiomers by capillary gas chromatography (GC) as N-trifluoroacetyl (TFA)-O-isopropyl derivatives using an l-valine-tert-butylamide modified polydimethylsiloxane chiral stationary phase (Chirasil-L-Val) were investigated. Good resolution was achieved using a temperature program from 100 °C (held for 3 min) to 160 °C at 1.5 °C min ^–1 and He as carrier gas. Very good selectivity and excellent detection limits of 0.25 µg L ^–1 (0.1 µg L ^–1 as Se) for each enantiomer were obtained by on-line coupling of the chiral capillary column with selenium-specific detection by inductively coupled plasma mass spectrometry (ICP-MS). Experimental parameter optimization is described in detail. This optimised GC-ICP-MS method was successfully applied to the determination of the optical purity of l-selenomethionine in commercial samples, to the determination of the enantiomeric ratio of selenomethionine in parenteral solutions used for human use and also to chiral Se speciation in selenized yeast.